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CVE-2023-5215

Libnbd: crash or misbehaviour when nbd server returns an unexpected block size

5.3 MediumFix available

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.81%Up 0.8 points since Sep 29, 2023
90%50%10%1%

What each source reports

CVE List Score used 5.3

Libnbd: crash or misbehaviour when nbd server returns an unexpected block size

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
CVE-2023-5215
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-241
Updated
2026-11-02
EUVDEUVD-2023-57545 5.3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
EUVD-2023-57545
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-fj2q-5f6j-5xf4 5.3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec...

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
GHSA-fj2q-5f6j-5xf4
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-241, CWE-252
Updated
2026-11-02
NVD 5.3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
CVE-2023-5215
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-241, CWE-252
Updated
2026-11-02
OSVALPINE-CVE-2023-5215 6.5

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
ALPINE-CVE-2023-5215
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSVAZL-31095 6.5

CVE-2023-5215 affecting package libnbd for versions less than 1.12.1-3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
AZL-31095
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 10 moreShow less
OSVAZL-34933 6.5

CVE-2023-5215 affecting package libnbd for versions less than 1.12.1-3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
AZL-34933
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 5.3

Libnbd: crash or misbehaviour when nbd server returns an unexpected block size

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
CVE-2023-5215
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-241
Updated
2026-11-02
OSVDEBIAN-CVE-2023-5215 6.5

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
DEBIAN-CVE-2023-5215
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2024:2204 5.3

Red Hat Security Advisory: libnbd security update

Record
RHSA-2024:2204
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVUBUNTU-CVE-2023-5215 5.3

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly.

Record
UBUNTU-CVE-2023-5215
CVSS 3.1
5.3 MediumCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVALSA-2024:2204 No score

Moderate: libnbd security update

Network Block Device (NBD) is a protocol for accessing Block Devices (hard disks and disk-like devices) over a Network. The libnbd is a userspace client library for writing NBD clients.

Security Fix(es):

  • libnbd: Malicious NBD server may crash libnbd (CVE-2023-5871)
  • libnbd: Crash or misbehaviour when NBD server returns an unexpected block size (CVE-2023-5215)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

Record
ALSA-2024:2204
Updated
2026-11-02
OSVCLSA-2026-1778007485 No score

libnbd: Fix of CVE-2023-5215

  • CVE-2023-5215: fix nbd_get_size returning negative value for sizes larger than INT64_MAX
Record
CLSA-2026-1778007485
Updated
2026-11-02
OSVMGASA-2024-0174 No score

Updated libnbd packages fix security vulnerability

A flaw was found in libnbd. A server can reply with a block size larger than 2^63 (the NBD spec states the size is a 64-bit unsigned value). This issue could lead to an application crash or other unintended behavior for NBD clients that doesn't treat the return value of the nbd_get_size() function correctly. (CVE-2023-5215)

Record
MGASA-2024-0174
Updated
2026-11-02
OSVopenSUSE-SU-2024:13278-1 No score

libnbd-1.18.0-1.1 on GA media

These are all security issues fixed in the libnbd-1.18.0-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:13278-1
Updated
2026-11-02
OSVSUSE-SU-2023:4222-1 No score

Security update for libnbd

This update for libnbd fixes the following issues:

  • Updated to version 1.18.1

  • Updated to version 1.18.0:

    • CVE-2023-5215: Fixed an issue where an NBD server returning an unexpected block size might crash an application (bsc#1215799).
Record
SUSE-SU-2023:4222-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libnbd
Alpine:v3.20
 before 1.18.0-r0
1.18.0-r0
libnbd
Alpine:v3.21
 before 1.18.0-r0
1.18.0-r0
libnbd
Alpine:v3.22
 before 1.18.0-r0
1.18.0-r0
libnbd
Alpine:v3.23
 before 1.18.0-r0
1.18.0-r0
libnbd
Alpine:v3.24
 before 1.18.0-r0
1.18.0-r0
libnbd
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
libnbd-bash-completion
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
libnbd-devel
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
nbdfuse
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
ocaml-libnbd
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
Show 41 moreShow less
Affected packages
PackageAffectedFixed
ocaml-libnbd-devel
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
python3-libnbd
AlmaLinux:9
From an advisory covering 2 CVEs
 before 1.18.1-3.el9
1.18.1-3.el9
libnbd
Azure Linux:2
 before 1.12.1-3
1.12.1-3
libnbd
Azure Linux:3
 before 1.12.1-3
1.12.1-3
libnbd
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
libnbd-bash-completion
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
libnbd-devel
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
nbdfuse
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
ocaml-libnbd
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
ocaml-libnbd-devel
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
python3-libnbd
TuxCare:AlmaLinux:9.2
 before 1.14.2-1.el9.tuxcare.els2
1.14.2-1.el9.tuxcare.els2
libnbd
Debian:12
 All versions, plus listed versions
1.14.2-11.16.1-11.16.2-11.16.3-11.16.4-1
Show 22 moreShow less
1.16.5-11.18.0-11.18.1-11.18.2-11.18.2-21.20.0-11.20.1-11.20.2-11.20.2-21.20.3-11.22.0-11.22.2-11.22.3-11.22.5-11.24.0-11.24.0-21.24.0-2.11.24.1-11.24.2-11.24.2-21.24.3-11.24.4-1
 None known
libnbd
Debian:13
 before 1.16.5-1
1.16.5-1
libnbd
Debian:14
 before 1.16.5-1
1.16.5-1
libnbd
Mageia:9
 before 1.15.8-3.1.mga9
1.15.8-3.1.mga9
libnbd
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-bash-completion
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-debuginfo
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-debugsource
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
nbdfuse
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
nbdfuse-debuginfo
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
ocaml-libnbd-debuginfo
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
python3-libnbd
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
python3-libnbd-debuginfo
Red Hat:enterprise_linux:9::appstream
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-debuginfo
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-debugsource
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd-devel
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
nbdfuse-debuginfo
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
ocaml-libnbd
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
ocaml-libnbd-debuginfo
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
ocaml-libnbd-devel
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
python3-libnbd-debuginfo
Red Hat:enterprise_linux:9::crb
From an advisory covering 2 CVEs
 before 0:1.18.1-3.el9
0:1.18.1-3.el9
libnbd
openSUSE:Leap 15.4
 before 1.18.1-150300.8.15.1
1.18.1-150300.8.15.1
libnbd
openSUSE:Leap 15.5
 before 1.18.1-150300.8.15.1
1.18.1-150300.8.15.1
libnbd
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.0.3-11.2.1-21.2.2-1ubuntu2
 None known
libnbd
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.6.3-11.8.5-11.10.2-11.10.5-1
 None known
libnbd
Ubuntu:24.04:LTS
 All versions, plus listed versions
1.16.4-11.18.1-11.18.2-11.18.2-1build11.18.2-21.18.2-2build11.20.0-1
 None known
libnbd
Ubuntu:25.10
 All versions, plus listed versions
1.22.0-11.22.2-1build11.22.2-1build2
 None known
libnbd
Ubuntu:26.10
 All versions, plus listed versions
1.24.2-1ubuntu11.24.2-2ubuntu11.24.3-1ubuntu1
 None known
libnbd
Ubuntu:26.04:LTS
 All versions, plus listed versions
1.22.2-1build21.24.0-2ubuntu11.24.1-1ubuntu61.24.2-1ubuntu1
 None known
libnbd
openSUSE:Tumbleweed
 before 1.18.0-1.1
1.18.0-1.1

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-5215 is a medium vulnerability (CVSS 5.3) in Redhat Libnbd, published September 28, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.81%, the 57th percentile. Fixed in libnbd 1.18.0-r0.

References

Show 27 moreShow less
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